Computed tomography-generated anthropometric measurements of orbital relationships in normal infants and children

OBJECTIVE The aim of this study was to develop soft-tissue and bony anthropometric orbital measurements in a normal pediatric population based upon CT scans. METHODS This was a retrospective stratified study of children with ages ranging from birth to 36 months. Head CT images for 204 children were available and obtained with 0.625-1-mm slice widths. Soft-tissue and bone windows were reviewed. Images were oriented in the Frankfort horizontal plane, and the intercanthal (IC), bony interorbital (IO), and bony lateral orbital (LO) distances were measured. Age group stratifications were 0-3, > 3-6, > 6-9, > 9-12, > 12-18, > 18-24, > 24-30, and > 30-36 months. Patients with known syndromes or craniofacial abnormalities were excluded. Statistical analysis included the mean, SD, SEM, 95% CI, and an evaluation of IO:LO ratio. RESULTS There was an average of 25.5 patients in each age group (range 25-27 patients). All soft-tissue and bony measurements consistently showed rapid increase from 0-6 months of age, which tapered after age > 12 months. The mean IC, bony IO, and bony LO distances started at 22.22 ± 1.13 mm, 14.16 ± 0.74 mm, and 65.56 ± 1.76 mm, and at 12 months were 27.74 ± 1.01 mm, 16.21 ± 0.75 mm, and 77.98 ± 1.57 mm, respectively. The bony LO position was equivalent to the lateral canthal position and measurements. The IC distance was approximately one-third the lateral canthal distance for all age groups. CONCLUSIONS This study established and reported normal anthropometric orbital measurements in a pediatric population using fine-cut craniofacial CT. These measurements are essential when evaluating children with craniofacial anomalies.